Knex Ball Machine Element - the Elliptica




Introduction: Knex Ball Machine Element - the Elliptica

About: K'nex is my thing!
Hey guys!

This is just a ball machine element that I made, meant to be added onto an existing machine. Check out the video to see how it works. Full credit for the concept goes to KageKumo.



Step 1: Parts List

Green - 174
White - 94
Blue - 146
Yellow - 33
Tan (or red) - 1

Dark Grey - 52
Light Grey - 4
Red - 8
Green - 34
Yellow - 90
White - 15
Orange - 4
Orange tabbed - 22
Blue 3D - 8
Purple 3D - 96

Medium wheel - 2 (pictured)
Tan Clips - 2
Blue Clips (tan can be used in their place) - 2
Blue Spacer - 10
Y-Connector - 10

Total: 807

You will also need roller coaster tubing (orange tubing will NOT work). You need either two pieces, at least 2 feet in length, or one piece, at least 5 feet in length.

Super! Let's get started.

Step 2: The Top Switcher

This is the part where the ball initially enters and is diverted down one of the two paths.

1: Build this piece
2: Make these two bits as well.
3-4: Slide those two parts over the piece you made in photo #1
5: Make this little bit
6: Add it on as well.
7-8: Now make this small part.
9: Get all these pieces ready
10: Add on the green/grey clip pieces as shown
11: Now slide the yellow rod through like so
12: Add on that silver spacer and tan clip to complete the assembly.

Great! Lets move onto the next step.

Step 3: Top Half

This is top part of the frame. Pretty simple!

1: Build this panel
2: Build another one too (mirror opposite)
3-5: Make this long piece.
6-7: Add that part you made in step one to connect the two panels you made in photos 1-2.
8-9: Make this tracking piece.
10: Build a second one (identical)
11: Connect the two tracking pieces to the piece that you assembled in photos 6-7.
12-13: Now add the other long piece onto the other side
14-15: Add in that path switcher as shown. The tan clip should be pointing down.


Step 4: Side Sections

These are just the two pieces of framing that support the whole structure.

1-2: Build this panel-esque piece
3-4: And this one
5-6: And now connect them as shown
7: Now build a mirror opposite of that same tower.

Super! Next step...

Step 5: Tracks

These are the two short tracks that direct the balls into the moving claw.

1-2: Build this part - it will be the "bumper" that the claw will hit.
3 : Build a second, identical one
4-6: Make this tracking piece. Note the placement of the blue rods
7: Build a second one
8: Add on the bumpers to the bottom of both track pieces.

Nearly finished!

Step 6: Rails

These are the railings that the claw will roll along. Very simple.

1-2: Build them up!


Step 7: The Claw

This is the magical claw. Go!

1: Build this flat piece (don't forget the green rods!)
2: Build a second piece (without the green rods...)
3: Make this
4: Snap it into that snowflake connector like so
5-6: Snap on the other half and connect the 3d connectors
7: Add on a blue spacer then a tan clip...
8: ...Then put the wheel on...
9: ...And finally, add on two more spacers and another tan (or blue) clip.
10-11: Repeat photos 7-9 on the other side.


Step 8: Assembly

The fun step!

1-3: Add the tracking pieces from step 5 onto the towers from step 4
4-5: Attach the rails from step 6 to the towers to get this frame
6-7: Drop the whole top frame onto the lower part. The connection is identical on both sides
8-9: Remove the orange connectors from the tower and slide them onto the tubing you have like so. If you have two tubing pieces, slide them just over either end of each piece, if you just have one piece of tubing (as in the photo), put two close to the center and two close to each end (this doesn't have to be exact, it will sort itself out.)
10-12: Clip the orange connectors back into the frame, and snap the tubing onto the orange tabbed connectors.
13: Depending on how much left over tubing you have, you can twist or tie it up however you want. I just clipped my ecxsess tubing into the lower part of the tower.

You're all done! Woohoo!

Step 9: Finished!

You're all done! All you need to do is to place the claw so that it catches the balls that roll off the paths on either side -  see the video in the intro to see where it should be.

Thanks very much for checking out this instructable! If you build your own Elliptica, please post a photo! I'll add it onto this step.

Thanks again,


1 Person Made This Project!


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6 years ago

it said nothing about silver spacers in the piece count


Nice man would be cool if the balls were collected and then lifted back up to the top


Reply 9 years ago on Introduction

Well the idea is that you put it into a ball machine that already has a lift system and basket to catch the balls. Thanks!!


9 years ago on Step 8

Thanks for the instructions it's a great element. I found that the orange tubing does work for me.


Finally got this to work. Just made a movie of my ball machine featuring the Eliptica. I don't know if you want credit or not just let me know and I'll be happy to edit it. Check it out:


Reply 9 years ago on Introduction

Super cool my friend! That's a mighty fine ball machine you've got there. Don't bother about giving credit. Thanks again!!


10 years ago on Introduction

Love it! Unfortunately, on mine, whenever it stops on one side, it always wobbles then leans towards the respective side. For example, say it is on the right side, it leans so far right the ball just hits the side and falls off. Any suggestions? I see on your example it stops perfectly.


Reply 10 years ago on Introduction

Thanks very much! As for your problem, just be very sure that you are on a flat surface (the "flat" floor in my living room is on too much of a slant for this to work properly on it..), and be sure that all the rods are snapped in correctly on the supports, if they are not in properly sometimes they can raise one of the sides up a hair. Hope that helps!


Reply 9 years ago on Introduction

Thanks for the advice. it is perfectly level and everything is where it is supposed to be. Any other tips that might help? It works most of the time. This is my flagship element on my k'nex ball machine. You actually inspired me to make my own ball machine.


Reply 9 years ago on Introduction

That's sweet dude! I don't really know how else I can help now, but if you could post a video of the problem I might be able to help..?


10 years ago on Introduction

Does it always turns good, so to speak?
Love it!

Purple Waffles
Purple Waffles

10 years ago on Step 9

Want a picture of it mounted up on my ball machine?